Have you ever noticed that the room containing your clothes dryer is the coldest room in your house? Ever wonder why?? Your clothes dryer is connected to a 4" diameter exhaust duct that is open to the outdoors. In the winter, cold air leaks in through the duct, through your dryer and into your house, while your heated air just pours right out! Try this yourself - with the dryer off, go outside and feel your heated air leaking out of the dryer vent. This is a substantial energy-loser! Many common discharge vents use a sheet metal flapper to try to reduce this air leakage. This is very primitive technology that does not provide a positive seal to stop the air leakage. Compounding the problem is that over time, lint clogs the flapper valve causing it to stay open. This is like leaving a window open! Conventional dryer vents can allow hot air into your home during the summer months, and cold air in during the winter. The Solution - Install a Dryer Vent Seal!